1 /* SPDX-License-Identifier: LGPL-2.1+ */
3 This file is part of systemd.
5 Copyright 2010 Lennart Poettering
13 #include <netinet/ip.h>
22 #include "alloc-util.h"
25 #include "format-util.h"
29 #include "parse-util.h"
30 #include "path-util.h"
31 #include "process-util.h"
32 #include "socket-util.h"
33 #include "string-table.h"
34 #include "string-util.h"
36 #include "user-util.h"
40 #if 0 /// UNNEEDED by elogind
42 # define IDN_FLAGS NI_IDN
47 static const char* const socket_address_type_table[] = {
48 [SOCK_STREAM] = "Stream",
49 [SOCK_DGRAM] = "Datagram",
51 [SOCK_RDM] = "ReliableDatagram",
52 [SOCK_SEQPACKET] = "SequentialPacket",
53 [SOCK_DCCP] = "DatagramCongestionControl",
56 DEFINE_STRING_TABLE_LOOKUP(socket_address_type, int);
58 int socket_address_parse(SocketAddress *a, const char *s) {
67 a->type = SOCK_STREAM;
72 /* IPv6 in [x:.....:z]:p notation */
78 n = strndupa(s+1, e-s-1);
81 if (inet_pton(AF_INET6, n, &a->sockaddr.in6.sin6_addr) <= 0)
82 return errno > 0 ? -errno : -EINVAL;
90 r = parse_ip_port(e, &port);
94 if (u <= 0 || u > 0xFFFF)
97 a->sockaddr.in6.sin6_family = AF_INET6;
98 a->sockaddr.in6.sin6_port = htobe16((uint16_t)u);
99 a->sockaddr.in6.sin6_port = htobe16(port);
100 a->size = sizeof(struct sockaddr_in6);
102 } else if (*s == '/') {
108 if (l >= sizeof(a->sockaddr.un.sun_path))
111 a->sockaddr.un.sun_family = AF_UNIX;
112 memcpy(a->sockaddr.un.sun_path, s, l);
113 a->size = offsetof(struct sockaddr_un, sun_path) + l + 1;
115 } else if (*s == '@') {
116 /* Abstract AF_UNIX socket */
120 if (l >= sizeof(a->sockaddr.un.sun_path) - 1)
123 a->sockaddr.un.sun_family = AF_UNIX;
124 memcpy(a->sockaddr.un.sun_path+1, s+1, l);
125 a->size = offsetof(struct sockaddr_un, sun_path) + 1 + l;
127 } else if (startswith(s, "vsock:")) {
128 /* AF_VSOCK socket in vsock:cid:port notation */
129 const char *cid_start = s + STRLEN("vsock:");
132 e = strchr(cid_start, ':');
136 r = safe_atou(e+1, &u);
137 r = safe_atou(e+1, &port);
141 n = strndupa(cid_start, e - cid_start);
143 r = safe_atou(n, &a->sockaddr.vm.svm_cid);
147 a->sockaddr.vm.svm_cid = VMADDR_CID_ANY;
149 a->sockaddr.vm.svm_family = AF_VSOCK;
150 a->sockaddr.vm.svm_port = u;
151 a->sockaddr.vm.svm_port = port;
152 a->size = sizeof(struct sockaddr_vm);
159 r = safe_atou(e+1, &u);
160 r = parse_ip_port(e + 1, &port);
164 if (u <= 0 || u > 0xFFFF)
167 n = strndupa(s, e-s);
169 /* IPv4 in w.x.y.z:p notation? */
170 r = inet_pton(AF_INET, n, &a->sockaddr.in.sin_addr);
175 /* Gotcha, it's a traditional IPv4 address */
176 a->sockaddr.in.sin_family = AF_INET;
177 a->sockaddr.in.sin_port = htobe16((uint16_t)u);
178 a->sockaddr.in.sin_port = htobe16(port);
179 a->size = sizeof(struct sockaddr_in);
183 if (strlen(n) > IF_NAMESIZE-1)
186 /* Uh, our last resort, an interface name */
187 idx = if_nametoindex(n);
191 a->sockaddr.in6.sin6_family = AF_INET6;
192 a->sockaddr.in6.sin6_port = htobe16((uint16_t)u);
193 a->sockaddr.in6.sin6_port = htobe16(port);
194 a->sockaddr.in6.sin6_scope_id = idx;
195 a->sockaddr.in6.sin6_addr = in6addr_any;
196 a->size = sizeof(struct sockaddr_in6);
201 r = safe_atou(s, &u);
202 r = parse_ip_port(s, &port);
206 if (u <= 0 || u > 0xFFFF)
209 if (socket_ipv6_is_supported()) {
210 a->sockaddr.in6.sin6_family = AF_INET6;
211 a->sockaddr.in6.sin6_port = htobe16((uint16_t)u);
212 a->sockaddr.in6.sin6_port = htobe16(port);
213 a->sockaddr.in6.sin6_addr = in6addr_any;
214 a->size = sizeof(struct sockaddr_in6);
216 a->sockaddr.in.sin_family = AF_INET;
217 a->sockaddr.in.sin_port = htobe16((uint16_t)u);
218 a->sockaddr.in.sin_port = htobe16(port);
219 a->sockaddr.in.sin_addr.s_addr = INADDR_ANY;
220 a->size = sizeof(struct sockaddr_in);
228 int socket_address_parse_and_warn(SocketAddress *a, const char *s) {
232 /* Similar to socket_address_parse() but warns for IPv6 sockets when we don't support them. */
234 r = socket_address_parse(&b, s);
238 if (!socket_ipv6_is_supported() && b.sockaddr.sa.sa_family == AF_INET6) {
239 log_warning("Binding to IPv6 address not available since kernel does not support IPv6.");
240 return -EAFNOSUPPORT;
247 int socket_address_parse_netlink(SocketAddress *a, const char *s) {
250 _cleanup_free_ char *sfamily = NULL;
258 if (sscanf(s, "%ms %u", &sfamily, &group) < 1)
259 return errno > 0 ? -errno : -EINVAL;
261 family = netlink_family_from_string(sfamily);
265 a->sockaddr.nl.nl_family = AF_NETLINK;
266 a->sockaddr.nl.nl_groups = group;
269 a->size = sizeof(struct sockaddr_nl);
270 a->protocol = family;
275 int socket_address_verify(const SocketAddress *a) {
278 switch (socket_address_family(a)) {
281 if (a->size != sizeof(struct sockaddr_in))
284 if (a->sockaddr.in.sin_port == 0)
287 if (!IN_SET(a->type, SOCK_STREAM, SOCK_DGRAM))
293 if (a->size != sizeof(struct sockaddr_in6))
296 if (a->sockaddr.in6.sin6_port == 0)
299 if (!IN_SET(a->type, SOCK_STREAM, SOCK_DGRAM))
305 if (a->size < offsetof(struct sockaddr_un, sun_path))
308 if (a->size > offsetof(struct sockaddr_un, sun_path)) {
310 if (a->sockaddr.un.sun_path[0] != 0) {
314 e = memchr(a->sockaddr.un.sun_path, 0, sizeof(a->sockaddr.un.sun_path));
318 if (a->size != offsetof(struct sockaddr_un, sun_path) + (e - a->sockaddr.un.sun_path) + 1)
323 if (!IN_SET(a->type, SOCK_STREAM, SOCK_DGRAM, SOCK_SEQPACKET))
330 if (a->size != sizeof(struct sockaddr_nl))
333 if (!IN_SET(a->type, SOCK_RAW, SOCK_DGRAM))
339 if (a->size != sizeof(struct sockaddr_vm))
342 if (!IN_SET(a->type, SOCK_STREAM, SOCK_DGRAM))
348 return -EAFNOSUPPORT;
352 int socket_address_print(const SocketAddress *a, char **ret) {
358 r = socket_address_verify(a);
362 if (socket_address_family(a) == AF_NETLINK) {
363 _cleanup_free_ char *sfamily = NULL;
365 r = netlink_family_to_string_alloc(a->protocol, &sfamily);
369 r = asprintf(ret, "%s %u", sfamily, a->sockaddr.nl.nl_groups);
376 return sockaddr_pretty(&a->sockaddr.sa, a->size, false, true, ret);
379 bool socket_address_can_accept(const SocketAddress *a) {
383 IN_SET(a->type, SOCK_STREAM, SOCK_SEQPACKET);
386 bool socket_address_equal(const SocketAddress *a, const SocketAddress *b) {
390 /* Invalid addresses are unequal to all */
391 if (socket_address_verify(a) < 0 ||
392 socket_address_verify(b) < 0)
395 if (a->type != b->type)
398 if (socket_address_family(a) != socket_address_family(b))
401 switch (socket_address_family(a)) {
404 if (a->sockaddr.in.sin_addr.s_addr != b->sockaddr.in.sin_addr.s_addr)
407 if (a->sockaddr.in.sin_port != b->sockaddr.in.sin_port)
413 if (memcmp(&a->sockaddr.in6.sin6_addr, &b->sockaddr.in6.sin6_addr, sizeof(a->sockaddr.in6.sin6_addr)) != 0)
416 if (a->sockaddr.in6.sin6_port != b->sockaddr.in6.sin6_port)
422 if (a->size <= offsetof(struct sockaddr_un, sun_path) ||
423 b->size <= offsetof(struct sockaddr_un, sun_path))
426 if ((a->sockaddr.un.sun_path[0] == 0) != (b->sockaddr.un.sun_path[0] == 0))
429 if (a->sockaddr.un.sun_path[0]) {
430 if (!path_equal_or_files_same(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path, 0))
433 if (a->size != b->size)
436 if (memcmp(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path, a->size) != 0)
443 if (a->protocol != b->protocol)
446 if (a->sockaddr.nl.nl_groups != b->sockaddr.nl.nl_groups)
452 if (a->sockaddr.vm.svm_cid != b->sockaddr.vm.svm_cid)
455 if (a->sockaddr.vm.svm_port != b->sockaddr.vm.svm_port)
461 /* Cannot compare, so we assume the addresses are different */
468 bool socket_address_is(const SocketAddress *a, const char *s, int type) {
469 struct SocketAddress b;
474 if (socket_address_parse(&b, s) < 0)
479 return socket_address_equal(a, &b);
482 bool socket_address_is_netlink(const SocketAddress *a, const char *s) {
483 struct SocketAddress b;
488 if (socket_address_parse_netlink(&b, s) < 0)
491 return socket_address_equal(a, &b);
494 const char* socket_address_get_path(const SocketAddress *a) {
497 if (socket_address_family(a) != AF_UNIX)
500 if (a->sockaddr.un.sun_path[0] == 0)
503 return a->sockaddr.un.sun_path;
506 bool socket_ipv6_is_supported(void) {
507 if (access("/proc/net/if_inet6", F_OK) != 0)
513 bool socket_address_matches_fd(const SocketAddress *a, int fd) {
520 b.size = sizeof(b.sockaddr);
521 if (getsockname(fd, &b.sockaddr.sa, &b.size) < 0)
524 if (b.sockaddr.sa.sa_family != a->sockaddr.sa.sa_family)
527 solen = sizeof(b.type);
528 if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &b.type, &solen) < 0)
531 if (b.type != a->type)
534 if (a->protocol != 0) {
535 solen = sizeof(b.protocol);
536 if (getsockopt(fd, SOL_SOCKET, SO_PROTOCOL, &b.protocol, &solen) < 0)
539 if (b.protocol != a->protocol)
543 return socket_address_equal(a, &b);
547 int sockaddr_port(const struct sockaddr *_sa, unsigned *ret_port) {
548 union sockaddr_union *sa = (union sockaddr_union*) _sa;
550 /* Note, this returns the port as 'unsigned' rather than 'uint16_t', as AF_VSOCK knows larger ports */
554 switch (sa->sa.sa_family) {
557 *ret_port = be16toh(sa->in.sin_port);
561 *ret_port = be16toh(sa->in6.sin6_port);
565 *ret_port = sa->vm.svm_port;
569 return -EAFNOSUPPORT;
573 #if 0 /// UNNEEDED by elogind
574 int sockaddr_pretty(const struct sockaddr *_sa, socklen_t salen, bool translate_ipv6, bool include_port, char **ret) {
575 union sockaddr_union *sa = (union sockaddr_union*) _sa;
580 assert(salen >= sizeof(sa->sa.sa_family));
582 switch (sa->sa.sa_family) {
587 a = be32toh(sa->in.sin_addr.s_addr);
592 a >> 24, (a >> 16) & 0xFF, (a >> 8) & 0xFF, a & 0xFF,
593 be16toh(sa->in.sin_port));
597 a >> 24, (a >> 16) & 0xFF, (a >> 8) & 0xFF, a & 0xFF);
604 static const unsigned char ipv4_prefix[] = {
605 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF
608 if (translate_ipv6 &&
609 memcmp(&sa->in6.sin6_addr, ipv4_prefix, sizeof(ipv4_prefix)) == 0) {
610 const uint8_t *a = sa->in6.sin6_addr.s6_addr+12;
614 a[0], a[1], a[2], a[3],
615 be16toh(sa->in6.sin6_port));
619 a[0], a[1], a[2], a[3]);
623 char a[INET6_ADDRSTRLEN];
625 inet_ntop(AF_INET6, &sa->in6.sin6_addr, a, sizeof(a));
631 be16toh(sa->in6.sin6_port));
645 if (salen <= offsetof(struct sockaddr_un, sun_path)) {
646 p = strdup("<unnamed>");
650 } else if (sa->un.sun_path[0] == 0) {
653 /* FIXME: We assume we can print the
654 * socket path here and that it hasn't
655 * more than one NUL byte. That is
656 * actually an invalid assumption */
658 p = new(char, sizeof(sa->un.sun_path)+1);
663 memcpy(p+1, sa->un.sun_path+1, sizeof(sa->un.sun_path)-1);
664 p[sizeof(sa->un.sun_path)] = 0;
667 p = strndup(sa->un.sun_path, sizeof(sa->un.sun_path));
681 r = asprintf(&p, "vsock:%u", sa->vm.svm_cid);
694 int getpeername_pretty(int fd, bool include_port, char **ret) {
695 union sockaddr_union sa;
696 socklen_t salen = sizeof(sa);
702 if (getpeername(fd, &sa.sa, &salen) < 0)
705 if (sa.sa.sa_family == AF_UNIX) {
706 struct ucred ucred = {};
708 /* UNIX connection sockets are anonymous, so let's use
709 * PID/UID as pretty credentials instead */
711 r = getpeercred(fd, &ucred);
715 if (asprintf(ret, "PID "PID_FMT"/UID "UID_FMT, ucred.pid, ucred.uid) < 0)
721 /* For remote sockets we translate IPv6 addresses back to IPv4
722 * if applicable, since that's nicer. */
724 return sockaddr_pretty(&sa.sa, salen, true, include_port, ret);
727 int getsockname_pretty(int fd, char **ret) {
728 union sockaddr_union sa;
729 socklen_t salen = sizeof(sa);
734 if (getsockname(fd, &sa.sa, &salen) < 0)
737 /* For local sockets we do not translate IPv6 addresses back
738 * to IPv6 if applicable, since this is usually used for
739 * listening sockets where the difference between IPv4 and
742 return sockaddr_pretty(&sa.sa, salen, false, true, ret);
745 int socknameinfo_pretty(union sockaddr_union *sa, socklen_t salen, char **_ret) {
747 char host[NI_MAXHOST], *ret;
751 r = getnameinfo(&sa->sa, salen, host, sizeof(host), NULL, 0, IDN_FLAGS);
753 int saved_errno = errno;
755 r = sockaddr_pretty(&sa->sa, salen, true, true, &ret);
759 log_debug_errno(saved_errno, "getnameinfo(%s) failed: %m", ret);
770 int socket_address_unlink(SocketAddress *a) {
773 if (socket_address_family(a) != AF_UNIX)
776 if (a->sockaddr.un.sun_path[0] == 0)
779 if (unlink(a->sockaddr.un.sun_path) < 0)
785 static const char* const netlink_family_table[] = {
786 [NETLINK_ROUTE] = "route",
787 [NETLINK_FIREWALL] = "firewall",
788 [NETLINK_INET_DIAG] = "inet-diag",
789 [NETLINK_NFLOG] = "nflog",
790 [NETLINK_XFRM] = "xfrm",
791 [NETLINK_SELINUX] = "selinux",
792 [NETLINK_ISCSI] = "iscsi",
793 [NETLINK_AUDIT] = "audit",
794 [NETLINK_FIB_LOOKUP] = "fib-lookup",
795 [NETLINK_CONNECTOR] = "connector",
796 [NETLINK_NETFILTER] = "netfilter",
797 [NETLINK_IP6_FW] = "ip6-fw",
798 [NETLINK_DNRTMSG] = "dnrtmsg",
799 [NETLINK_KOBJECT_UEVENT] = "kobject-uevent",
800 [NETLINK_GENERIC] = "generic",
801 [NETLINK_SCSITRANSPORT] = "scsitransport",
802 [NETLINK_ECRYPTFS] = "ecryptfs",
803 [NETLINK_RDMA] = "rdma",
806 DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(netlink_family, int, INT_MAX);
808 static const char* const socket_address_bind_ipv6_only_table[_SOCKET_ADDRESS_BIND_IPV6_ONLY_MAX] = {
809 [SOCKET_ADDRESS_DEFAULT] = "default",
810 [SOCKET_ADDRESS_BOTH] = "both",
811 [SOCKET_ADDRESS_IPV6_ONLY] = "ipv6-only"
814 DEFINE_STRING_TABLE_LOOKUP(socket_address_bind_ipv6_only, SocketAddressBindIPv6Only);
816 SocketAddressBindIPv6Only parse_socket_address_bind_ipv6_only_or_bool(const char *n) {
819 r = parse_boolean(n);
821 return SOCKET_ADDRESS_IPV6_ONLY;
823 return SOCKET_ADDRESS_BOTH;
825 return socket_address_bind_ipv6_only_from_string(n);
828 bool sockaddr_equal(const union sockaddr_union *a, const union sockaddr_union *b) {
832 if (a->sa.sa_family != b->sa.sa_family)
835 if (a->sa.sa_family == AF_INET)
836 return a->in.sin_addr.s_addr == b->in.sin_addr.s_addr;
838 if (a->sa.sa_family == AF_INET6)
839 return memcmp(&a->in6.sin6_addr, &b->in6.sin6_addr, sizeof(a->in6.sin6_addr)) == 0;
841 if (a->sa.sa_family == AF_VSOCK)
842 return a->vm.svm_cid == b->vm.svm_cid;
848 int fd_inc_sndbuf(int fd, size_t n) {
850 socklen_t l = sizeof(value);
852 r = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &value, &l);
853 if (r >= 0 && l == sizeof(value) && (size_t) value >= n*2)
856 /* If we have the privileges we will ignore the kernel limit. */
859 if (setsockopt(fd, SOL_SOCKET, SO_SNDBUFFORCE, &value, sizeof(value)) < 0)
860 if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &value, sizeof(value)) < 0)
866 int fd_inc_rcvbuf(int fd, size_t n) {
868 socklen_t l = sizeof(value);
870 r = getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &value, &l);
871 if (r >= 0 && l == sizeof(value) && (size_t) value >= n*2)
874 /* If we have the privileges we will ignore the kernel limit. */
877 if (setsockopt(fd, SOL_SOCKET, SO_RCVBUFFORCE, &value, sizeof(value)) < 0)
878 if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &value, sizeof(value)) < 0)
883 #if 0 /// UNNEEDED by elogind
884 static const char* const ip_tos_table[] = {
885 [IPTOS_LOWDELAY] = "low-delay",
886 [IPTOS_THROUGHPUT] = "throughput",
887 [IPTOS_RELIABILITY] = "reliability",
888 [IPTOS_LOWCOST] = "low-cost",
891 DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(ip_tos, int, 0xff);
893 bool ifname_valid(const char *p) {
896 /* Checks whether a network interface name is valid. This is inspired by dev_valid_name() in the kernel sources
897 * but slightly stricter, as we only allow non-control, non-space ASCII characters in the interface name. We
898 * also don't permit names that only container numbers, to avoid confusion with numeric interface indexes. */
903 if (strlen(p) >= IFNAMSIZ)
906 if (dot_or_dot_dot(p))
910 if ((unsigned char) *p >= 127U)
913 if ((unsigned char) *p <= 32U)
916 if (IN_SET(*p, ':', '/'))
919 numeric = numeric && (*p >= '0' && *p <= '9');
929 bool address_label_valid(const char *p) {
934 if (strlen(p) >= IFNAMSIZ)
938 if ((uint8_t) *p >= 127U)
941 if ((uint8_t) *p <= 31U)
950 int getpeercred(int fd, struct ucred *ucred) {
951 socklen_t n = sizeof(struct ucred);
958 r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &u, &n);
962 if (n != sizeof(struct ucred))
965 /* Check if the data is actually useful and not suppressed due to namespacing issues */
966 if (!pid_is_valid(u.pid))
969 /* Note that we don't check UID/GID here, as namespace translation works differently there: instead of
970 * receiving in "invalid" user/group we get the overflow UID/GID. */
976 int getpeersec(int fd, char **ret) {
977 _cleanup_free_ char *s = NULL;
988 if (getsockopt(fd, SOL_SOCKET, SO_PEERSEC, s, &n) >= 0)
1005 int getpeergroups(int fd, gid_t **ret) {
1006 socklen_t n = sizeof(gid_t) * 64;
1007 _cleanup_free_ gid_t *d = NULL;
1017 if (getsockopt(fd, SOL_SOCKET, SO_PEERGROUPS, d, &n) >= 0)
1020 if (errno != ERANGE)
1026 assert_se(n % sizeof(gid_t) == 0);
1029 if ((socklen_t) (int) n != n)
1040 const struct sockaddr *sa, socklen_t len,
1044 struct cmsghdr cmsghdr;
1045 uint8_t buf[CMSG_SPACE(sizeof(int))];
1047 struct msghdr mh = {
1048 .msg_name = (struct sockaddr*) sa,
1050 .msg_control = &control,
1051 .msg_controllen = sizeof(control),
1053 struct cmsghdr *cmsg;
1055 assert(transport_fd >= 0);
1058 cmsg = CMSG_FIRSTHDR(&mh);
1059 cmsg->cmsg_level = SOL_SOCKET;
1060 cmsg->cmsg_type = SCM_RIGHTS;
1061 cmsg->cmsg_len = CMSG_LEN(sizeof(int));
1062 memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
1064 mh.msg_controllen = CMSG_SPACE(sizeof(int));
1065 if (sendmsg(transport_fd, &mh, MSG_NOSIGNAL | flags) < 0)
1071 #if 0 /// UNNEEDED by elogind
1072 int receive_one_fd(int transport_fd, int flags) {
1074 struct cmsghdr cmsghdr;
1075 uint8_t buf[CMSG_SPACE(sizeof(int))];
1077 struct msghdr mh = {
1078 .msg_control = &control,
1079 .msg_controllen = sizeof(control),
1081 struct cmsghdr *cmsg, *found = NULL;
1083 assert(transport_fd >= 0);
1086 * Receive a single FD via @transport_fd. We don't care for
1087 * the transport-type. We retrieve a single FD at most, so for
1088 * packet-based transports, the caller must ensure to send
1089 * only a single FD per packet. This is best used in
1090 * combination with send_one_fd().
1093 if (recvmsg(transport_fd, &mh, MSG_NOSIGNAL | MSG_CMSG_CLOEXEC | flags) < 0)
1096 CMSG_FOREACH(cmsg, &mh) {
1097 if (cmsg->cmsg_level == SOL_SOCKET &&
1098 cmsg->cmsg_type == SCM_RIGHTS &&
1099 cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
1107 cmsg_close_all(&mh);
1111 return *(int*) CMSG_DATA(found);
1114 ssize_t next_datagram_size_fd(int fd) {
1118 /* This is a bit like FIONREAD/SIOCINQ, however a bit more powerful. The difference being: recv(MSG_PEEK) will
1119 * actually cause the next datagram in the queue to be validated regarding checksums, which FIONREAD doesn't
1120 * do. This difference is actually of major importance as we need to be sure that the size returned here
1121 * actually matches what we will read with recvmsg() next, as otherwise we might end up allocating a buffer of
1122 * the wrong size. */
1124 l = recv(fd, NULL, 0, MSG_PEEK|MSG_TRUNC);
1126 if (IN_SET(errno, EOPNOTSUPP, EFAULT))
1139 /* Some sockets (AF_PACKET) do not support null-sized recv() with MSG_TRUNC set, let's fall back to FIONREAD
1140 * for them. Checksums don't matter for raw sockets anyway, hence this should be fine. */
1142 if (ioctl(fd, FIONREAD, &k) < 0)
1148 int flush_accept(int fd) {
1150 struct pollfd pollfd = {
1156 /* Similar to flush_fd() but flushes all incoming connection by accepting them and immediately closing them. */
1161 r = poll(&pollfd, 1, 0);
1171 cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
1176 if (errno == EAGAIN)
1186 struct cmsghdr* cmsg_find(struct msghdr *mh, int level, int type, socklen_t length) {
1187 struct cmsghdr *cmsg;
1191 CMSG_FOREACH(cmsg, mh)
1192 if (cmsg->cmsg_level == level &&
1193 cmsg->cmsg_type == type &&
1194 (length == (socklen_t) -1 || length == cmsg->cmsg_len))
1200 int socket_ioctl_fd(void) {
1203 /* Create a socket to invoke the various network interface ioctl()s on. Traditionally only AF_INET was good for
1204 * that. Since kernel 4.6 AF_NETLINK works for this too. We first try to use AF_INET hence, but if that's not
1205 * available (for example, because it is made unavailable via SECCOMP or such), we'll fall back to the more
1206 * generic AF_NETLINK. */
1208 fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC, 0);
1210 fd = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_GENERIC);